79 research outputs found
Characteristics of the polymer transport in ratchet systems
Molecules with complex internal structure in time-dependent periodic
potentials are studied by using short Rubinstein-Duke model polymers as an
example. We extend our earlier work on transport in stochastically varying
potentials to cover also deterministic potential switching mechanisms,
energetic efficiency and non-uniform charge distributions. We also use currents
in the non-equilibrium steady state to identify the dominating mechanisms that
lead to polymer transportation and analyze the evolution of the macroscopic
state (e.g., total and head-to-head lengths) of the polymers. Several numerical
methods are used to solve the master equations and nonlinear optimization
problems. The dominating transport mechanisms are found via graph optimization
methods. The results show that small changes in the molecule structure and the
environment variables can lead to large increases of the drift. The drift and
the coherence can be amplified by using deterministic flashing potentials and
customized polymer charge distributions. Identifying the dominating transport
mechanism by graph analysis tools is found to give insight in how the molecule
is transported by the ratchet effect.Comment: 35 pages, 17 figures, to appear in Phys. Rev.
Vulnerable warriors: the atmospheric marketing of military and policing equipment before and after 9/11
In this article, we analyse changes in the circulation of advertisements of policing products at security expos between 1995 and 2013. While the initial aim of the research was to evidence shifts in terrorist frames in the marketing of policing equipment before and after 9/11, our findings instead suggested that what we are seeing is the rise of marketing to police as âvulnerable warriorsâ, law enforcement officers in need of military weapons both for their offensive capabilities and for the protection they can offer to a police force that is always under threat
A neutron diffuse scattering study of PbZrO<sub>3</sub> and Zr-rich PbZr<sub>1-x</sub>Ti<sub>x</sub>O<sub>3</sub>
A combined neutron diffuse scattering study and model analysis of the antiferroelectric crystal PbZrO3is described. Following on from earlier X-ray diffuse scattering studies, supporting evidence for disordering of oxygen octahedral tilts and Pb displacements is shown in the high-temperature cubic phase. Excess diffuse scattering intensity is found at theMandRpoints in the Brillouin zone. A shell-model molecular dynamics simulation closely reproduces the neutron diffuse scattering pattern. Both in-phase and antiphase tilts are found in the structural model, with in-phase tilts predominating. The transition between disordered and ordered structure is discussed and compared with that seen in Zr-rich PbZr1âxTixO3.</jats:p
An Adaptive Finite Element Method for the H- Ï Formulation of Time-dependent Eddy Current Problems
Abstract No. 461 With rapidly growing use of catheter-directed therapies, preservation of whole-organ gross vascular anatomy using perfusion fixation is an important research tool in interventional radiology
04:12 PM Abstract No. 333 How does number of microspheres affect absorbed-dose uniformity in Y90 radioembolization? An in vivo 3D evaluation in a porcine model
- âŠ